MBR Energy Consumption: Comparing Operating Full-Scale Plants

Early in the life-cycle of a wastewater treatment project, facility management, operators, and designers select a treatment process alternative among competing feasible technologies. The process selection decision process balances tradeoffs such as capital and operating costs with multiple required performance factors such as treatment effectiveness to meet effluent permit limits, ease of operation, etc. Proven technologies, such as conventional activated sludge (CAS) treatment, offer decades of operating data on which to base life-cycle cost estimates, providing confidence in these estimates. Newer technologies, such as Membrane Bioreactors (MBRs), lack the depth of available capital and operation cost data on which to base project life-cycle costs. MBR technology has evolved over the last decade to include improvements intended to reduce energy consumption. Published energy consumption values show considerable variability. This paper attempts to reconcile energy consumption discrepancies in operating MBR facilities and should provide decision makers increased confidence in operating cost estimates for this technology in order to develop accurate life-cycle costs.